array_count_values function does not work on multidimentional arrays.If $score[][] is a bidimentional array, the command"array_count_values ($score)" return the error message "Warning: Can only count STRING and INTEGER values!".

alwaysdrunk's comment only works if you can trust the client web browser. Using this function doesn't validate that every necessary field exists -- only that every field that was submitted has a value in it. Thus if an attacker wished to force a null value into one of the fields, he could (rather easily) construct a modified form without the field and submit THAT.

Besides, you really ought to be validating each field anyway if you're taking user input.